This invention relates to chelating agents and, more particularly, to chelating agents for heavy metal ions such as mercury and improved methods for chelating such ions.
As is known, dimercaprol (2,3-dimercapto-1-propanol) is used as a detoxifying agent or chelating or complexing agent in mercury poisoning and against the toxicity of other heavy metal ions. However, dimercaprol suffers from a number of disadvantages and shortcomings. Thus, dimercaprol is not useful for iron, cadmium or selenium poisoning because the resulting Dimercaprol-metal complex is more toxic than the metal itself, especially to the kidney. Moreover, dimercaprol is not water-soluble and can be used only as a dispersion in peanut oil. Also, dimercaprol-metal complexes break down easily in an acid medium and therefore production of an alkaline urine is desired to afford protection to the kidney during dimercaprol therapy.
There is a need, therefore, for improved chelating or complexing agents for heavy metal ions which do not suffer from these drawbacks. There is also a need for such improved agents which are useful in removing heavy metal ions (e.g., mercury) from aqueous systems such as industrial discharges or waste waters.